Reference materials are crucial for analytical testing workflow. Reference materials ensure accuracy in testing as there are a number of quality control programs in place. All methods are validated and measurement systems are calibrated for the purpose. The world of reference materials is quite vast and it is inclusive of certified reference materials, quality grades reference materials, analysis certificates, and other concepts such as metrological traceability.
SI Units of reference materials and metrological traceability Metrological traceability is extremely important in the world of reference materials. One of the fundamental terms in metrological traceability is the SI unit of measurement. SI, or the International Systems of Units defines the 7 units of measure as the basic set which is used to derive all other SI units. The two most commonly used SI units of measure for traceability of reference materials are kg. and mole. In a nutshell, metrological traceability simply means measurements can be compared in a meaningful manner across different places at different times using different equipment by different people. It is important that the measurement result is related to a reference through an unbroken chain of calibrations and it should be documented. It should also be traced back to the SI unit of measurement.
According to the reference standards suppliers in Canada, the reference material hierarchy is inclusive of five major quality grades. It ranges from national metrology and other primary standards to CRMs (Certified Reference Materials), RMs (Reference Materials), Analytical Standards, and research chemicals or research grade. You must know that traceability requirements and apparently level of certification increase with each higher level. Chemical reference standards suppliers in Canada say that reference material producers are supposed to meet all ISO requirements for manufacturing CRMs and RMs. These ISO requirements are ISO 17034, ISO/IEC 17025, and ISO Guide 31. Parameters in Each Grade of Reference Material Purity and Identity of the material are incorporated in the Certificate of Analysis for each quality grade. Content and Stability are needed for the primary standards of CRM and RM defined by the ISO standards. Homogeneity again is needed for the primary standards, CRM, and RM; however, this parameter is not applicable for lower quality grades. Uncertainty and Traceability are confined to just primary standards and CRM. Pharmaceutical Reference Standards suppliers say that in the pharmaceutical world, secondary standards are CRMs and RMs; however, there are 2 different types of traceability. Those are traceability to the SI unit of measurement for ISO defined CRM and traceability to the primary compendial standard. For more information related to chemical reference standards suppliers in Canada, feel free to get in touch with us.